Air-speed responsive device



April 24, 1951 RUSSELL 2,550,603

AIR-SPEED RESPONSIVE DEVICE Filed Aug. 50, 1945 NVENTOR' MH 7 THE W J B. RUSSELL RNEY- Patented Apr. 24, 1951 2,550,603 AIR-SPEED RESPONSIVE DEVICE Matthew J. B. Russell, Brooklyn, N. Y., assignor' to Bendix Aviation Corporation,

Teterboro,

N. J a corporation of Delaware Application August 30, 1945;Se1ialN0. 613,636

This invention relates to an air speed responsive device wherein the speed of operation of centrifugal means controlled by the pitot pressure due to the airspeed of a craft, will register airspeed; the air mileage being a product of airspeed and time.

An object of this invention is to provide an airspeed responsive device in which the movement of a pressure responsive diaphragm actuated by the impact pressure obtained from a Pitot tube is applied to a lever system to close a circuit to operate a centrifugal means, the linear move ment of the centrifugal means due to its speed of operation being applied to the lever system to counter-balance the movement of the diaphragm to open the circuit, the average speed of the centrifugal means being a measure of airspeed of the craft.

Another object of the present invention is to provide an airspeed responsive device of the character described in which the pressure responsive diaphragm of an airspeed indicator is used to control the centrifugal means.

Still another object of this invention is to provide an airspeed responsive device of the character described with a compensating member to correct for varying air density.

A further object of the present invention is to provide an air mileage indicator of the character described in which the centrifugal means may be driven by an electric motor, the circuit for said motor being controlled by a pair of contacts adapted to be opened and closed by the bal ance and unbalance of the lever system.

Yet another object of the present invention is to provide a highly improved air mileage indicator of the character described which shall be relatively inexpensive to manufacture, positive in its operation, and practical and efiicient to a high degree in use.

Other objects of this invention will in part be obvious and in part hereinafter pointed out.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the constructions hereinafter described, and of which the scope of this application will be indicated by the appended claims.

In the accompanying drawing in which one embodiment of the present invention is illustrated, the single figure in the drawing is a diagrammatic view of an airspeed responsive device in which an electric motor is used to drive the centrifugal means represented by a ball governor. I

Referring now in detail to the single figure of Claims. (01. 73-182) the drawing, Hi designates an airspeed indicator of the conventional type comprising a pressure responsive bellows ll within the-casing l2. The interior of the bellows ll is connected by a pipe line l3 to the impact or dynamic, pressure source of a Pitot tube (not shown). The interior of casing I2 is connected by lines M and It to the static pressure of the Pitot tube.

The lower face of the bellows II is provided with a rack I5 adapted to be moved up and down upon expansion and contraction of the bellows. Fixed to a horizontally disposed shaft I? which extends beyond the rear of easing i2, is a pinion l8. Rotation of the pinion by movement of the rack will rotate shaft 11 and a pointer it over the face of the dial 29 of the instrument by way of a gear sector 2! fixed to shaft I! and a gear 22 fixed to a shaft 23 on which the pointer i9 is fixed. A reading of the pointer IS with respect to the dial 28 will give indicated airspeed.

Fixed to the extreme end of shaft H is a pinion 24 adapted to mesh with a rack 25. The lower end of the rack 25 is pivoted to a lever 25.? whose fulcrum is indicated as at 27. The opposite end of lever 26 is provided with an electrical contact 28, for the purposes hereinafter appearing. A spring 29 fixed to said lever nearthe contact, aids in returning the lever to its horizontal position.

Means is now provided to operate a governor at a speed in proportion to the airspeed of a craft. To this end there isprovided an electric motor at having a shaft 3|. The upper end of the shaft 3| is provided with a centrifugal means, herein disclosed as a conventional ball governor 32. The ball governor is provided at its upper end with a peripheral slotted member 33 which is engaged by a pin 34 in a lever 35 whose fulcrum is indicated as being at 36A. The other end of lever 35 is provided with a depending electrical contact 36 adapted to engage the electrical contact 28 on lever 26.

Contact 36 is connected by wire 31 to one side of a power supply, herein indicated as a battery 38. The other side of said battery is connected by wire 39 through said electric motor 30 and by wire 49 to the electric contact 28.

In operation, the expansion of the bellows H will move the rack it to rotate the pinion l8. Shaft ll is thus rotated to rotate the pinion 24 to move rack 25 downwardly. Lever 2%; will thus be rotated in a counter-clockwise direction to close the contacts 28 and 363. In closing the contacts, the electrical circuit through motor 3%! and battery 38 is completed to operate the electric motor.

Operation of the electric motor will operate the ball governor 32. Dependent upon the speed of the electric motor, the peripheral member 33 will be moved downwardly to rotate the lever 35 in a clockwise direction. Clockwise rotation of the lever 35 about the fulcrum 36A will tend to disengage the contact 35 from the contact 28. When the motor has reached a speed determined by the expansion of the bellows H the motor circuit will be opened, tending to stop the motor.

In opening the motor circuit, the speed of the motor is reduced permitting the, ballgovernor to return toward its initial position. Upon upward movement of the governor, the contacts. 36 and 28 are again closed to operate the; motor:

30. Thus, for a given airspeed of the craft as registered by the bellows the average speed of the motor 36 will register the airspeed of the craft.

The lower end of shafti3| as influenced by the density compensator aneroid 4| (to be presently described) may be connected by any suitable gearing (not shown) to a tachometer (not shown) or other suitable device to indicate true airspeed. The shaft may-also be connected by suitable means to a Geneva mechanism (not shown) or any other indicating means-to indicate the air mileage of the craft over a period of time.

Means is now provided to correct the air mileageindicator for changes in air density. To this end there is provided a second bellows or aneroid 4| enclosed in a casing 42, the interior of the casing 42 being connected to the static pressure of the Pitot tube by way of pipe line l5.

The lower face of the bellows 4|.is provided with a depending rod 43, the lower end of which is pivoted to an arm 44; Arm 44 is pivoted at one end as at 45, the other end being formed with a depending finger 46 which abuts against the pivoted lever between the fulcrum 36A and the contact 35.

Upon decrease in air density, bellows 4| will expand to rotate the lever 35 in a counter clockwise direction by way of rod 43 and arm 44. As previously described, clockwise rotation of the lever 35 will tend to open the contacts 36 and 23. In this way the lowering of air density will oppose the governor 32 in opening the contacts.

It has been found that flying at various altitudes the airspeed indicator as shown herein, is prone to error due to the varying air densities. The present invention has been disclosed as being operative by a conventional airspeed indicator in which no corrections are made for flight at varying altitudes. To correct for the slight error in the airspeed indicator, the compensating bellows 4| has been added inv the present invention. Where a compensated, true airspeed indicator is used to rotate the lever 26, the compensating bellows 4| may be eliminated from the present invention, the speed of the motor 30 being then in direct proportion to the true airspeed;

It will thus be seen that there is provided an air speed responsive device in which the several objects of this invention are achieved, and which is well adapted to meet the conditions ofpractical use.

As various possible embodiments may be madeof the above invention, and as various changes might be made in the embodiments disclosed herein, it is to be understood that all matters set forth, or shown in the accompanying drawing, are to be interpreted as illustrative, and not in a limiting sense.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. An airspeed responsive device comprising a pressure responsive member actuated by the impact pressure on one side thereof and by the static pressure on the other side thereof, a lever actuated by the movement of said pressure responsive membenia contact on saidlever, a ball governor, a'motor for rotating said ball governor, a second lever actuated by the linear motion of said ball governor, a second contact on said second lever. adapted to engage and disengage said first contact upon movement of said levers, a power source connected to said motor and said contacts for operating said motor by the opening and closingof saidcontacts to rotate said governor at aspeed proportional to the airspeed of a craft, and a second" pressure responsive member responsive to the static pressure coacting with one of said levers in aiding relationship with said first pressure responsivemember to compensate the rotational speedof said governor for varying air density.

2. An airspeed responsive device comprising a pressure responsive member actuated by the impact pressure on one side thereof and by the static'pressure on the otherside thereof, a lever actuated by the movement of-saidpressureresponsive member, a contact on said lever, a ball governor, a motor for rotating said ball governor; a second lever actuatedby the linear motion of said ball governor, a second contact on said second lever adapted to engage and disengage.

said first contact upon movement of said levers,

, a power source connected to said motor and said contacts for operating said motor by the opening and closing of said contacts to rotatesaid governor at a speed proportional to the airspeed of a craft, and a second pressureresponsive member actuated by the. static pressure coacting with said second lever in opposition to the linear movement of the ball governor for compensating the rotational speed of i said ball. governor for varying air density..

3. An airspeed responsive device comprising an airspeed indicator havingra yieldable'wall actuated by impact pressure on one side thereof and by static. pressure on theother side thereof, a

lever system drivably connected to said yieldable walland actuated by the movement thereof and including circuit making and breaking means between elements of the leverv system. opened and closed by the. movement .of .said' wall, centrifugal means adapted to coact with-said lever system andhaving a linear movement to balance the force exertedon said lever system by said yieldable wall, an electric motor. controlled by the circuit making and .breaking means for rotating said'centrifugalimeans,.a second yieldable wall actuated by static pressure drivably connected to said circuit making and breaking means and to said centrifugal means to compensate for the varying air. density, the. average speed of said centrifugal means being va .function of the differential pressure affecting said first named yieldable wall.

4. An airspeed responsive devicecomprising a yieldable wall actuated by impact pressure on one side thereof and by staticv pressure on the lever system positioned adjacent to said first lever system, an electrical switch interconnecting said first and second lever systems for transmitting a force. therebetween, said switch being other side thereof, a first lever system actuated by the movement of said yieldable wall, a second.

opened and closed by the movements of said lever systems, an electric motor controlled by said switch, a ball governor rotatively driven by said electric motor operatively connected to said second lever system and having a linear movement which is applied to said second lever system to balance the force applied to the first lever system by the yieldable wall, the rotation of said ball governor being controlled at a speed proportional to the air speed by the movements of the lever systems in opening and closing the switch, and a second yieldable wall actuated by the static pressure cooperating with the movement of said governor and connected with the second lever system to modify the effect of said first named yieldable wall to compensate for varying air density.

5. An airspeed responsive device comprising, an airspeed indicator having a pressure responsive member actuated on one side thereof by the impact pressure and the other side by the static pressure of a Pitot tube, a lever actuated by the expansion and contraction of the pressure responsive member, a contact on said lever, a ball REFERENCES CITED The following references are of record in the 10 file of this patent:

governor, a motor to rotate said ball governor, 96

a second lever actuated by the linear motion of said ball governor, a second contact on said second lever adapted to engage and disengage said first contact upon movement of said levers,

UNITED STATES PATENTS Number Name Date 1,451,064 Dunajeff Apr. 10, 1923 1,677,835 Linderman July 17, 1928 1,679,293 Dawley July 31, 1928 1,842,238 Benesh Jan. 19, 1932 1,993,707 Rosecrans Mar 5, 1935 2,094,196 Town Sept. 28, 1937 2,251,498 Schwein Aug. 5, 1941 2,309,015 Royer Jan. 19, 1943 2,441,381 Anderson May 11, 1948 FOREIGN PATENTS Number Country Date 782,065 France Mar. 11, 1935 353,994 Great Britain Aug. 6, 1931 482,766 Germany Sept. 19, 1929 

